James Yenbamroong, who founded satellite communications provider mu Space Corp, tweeted that the “SpaceX team reached out to us today to help connect to Thai govt”.

He added: “For pumps, cave has narrowest 70cm cross section. For vertical drill, it’s about 1/2 mile down and tricky.”

Mr Musk’s team could help with location tracking, water pumping or battery power, the Thai government said.

Maybe worth trying: insert a 1m diameter nylon tube (or shorter set of tubes for most difficult sections) through cave network & inflate with air like a bouncy castle. Should create an air tunnel underwater against cave roof & auto-conform to odd shapes like the 70cm hole.